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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Three-dimensional elasticity solution of an infinite plate with a circular hole

The elasticity problem for a thick plate with a circular hole is formulated in a systematic fashion by using the z-component of the Galerkin vector and that of Muki's harmonic vector function. The problem was originally solved by Alblas. The reasons for reconsidering it are to develop a technique which may be used in solving the elasticity problem for a multilayered plate and to verify and extend the results given by Alblas. The problem is reduced to an infinite system of algebraic equations which is solved by the method of reduction. Various stress components are tabulated as functions of a/h, z/h, r/a, and nu, a and 2h being the radius of the hole and the plate thickness and nu, the Poisson's ratio. The significant effect of the Poisson's ratio on the behavior and the magnitude of the stresses is discussed.

Delale, F.↗
NASA NTRS1982

QCSEE under-the-wing engine acoustic data

Both an over-the-wing (OTW) and an under-the-wing (UTW) experimental engine are discussed. The UTW engine had a variable-geometry fan exhaust nozzle and a variable-pitch fan that provided quick-response reverse thrust capability. An automatic digital control enabled optimal engine operation under all steady-state conditions as well as during forward and reverse thrust transient operation. The engine was tested at the Engine Noise Test Facility alone and with wind and flap segments to simulate an installation on a short-haul transport aircraft. The engine acoustic configuration was varied to give 14 test configurations. All of the acoustic test results from the UTW program at Lewis are presented as 1/3-octave-band sound pressure level (SPL) tabulations for all of the test points and some narrow-band spectra and 1/3-octave-band data plots for selected conditions.

Bloomer, H. E.↗
NASA NTRS1982

Preliminary Analysis of STS-3 Entry Heat-Transfer Data for the Orbiter Windward Centerline

A preliminary analysis of heat transfer data on the space shuttle orbiter windward centerline for the STS-3 mission entry is presented. Temperature-time history plots for each measurement location and tabulated wall temperature and convective heating rate data at 21 selected trajectory points are included. The STS-3 flight data are also compared with predictions by two approximation methods for computing convective heat transfer rates in equilibrium air.

Throckmorton, D. A.↗
NASA NTRS1982

Geometric error characterization and error budgets

Procedures used in characterizing geometric error sources for a spaceborne imaging system are described using the LANDSAT D thematic mapper ground segment processing as the prototype. Software was tested through simulation and is undergoing tests with the operational hardware as part of the prelaunch system evaluation. Geometric accuracy specifications, geometric correction, and control point processing are discussed. Cross track and along track errors are tabulated for the thematic mapper, the spacecraft, and ground processing to show the temporal registration error budget in pixel (42.5 microrad) 90%.

Beyer, E.↗
NASA NTRS1979

Evaluation of the IMP-16 microprocessor orbit determination system filter

The results of the numerical tests performed in evaluating the interplanetary monitoring platform-16 orbit determination system are presented. The system is capable of performing orbit determination from satellite to satellite tracking data in applications technology satellite range and range rate format. The estimation scheme used is a Kalman filter, sequential (recursive) estimator. Descriptions of the tests performed and tabulations of the numerical results are included.

Shenitz, C. M.↗
NASA NTRS1982

IUE data reduction: Wavelength determinations and line identifications using a VAX/750 computer

A fully automated, interactive system for determining the wavelengths of features in extracted IUE spectra is described. Wavelengths are recorded from video displays of expanded plots of individual orders using a movable cursor, and then corrected for IUE wavelength scale errors. The estimated accuracy of an individual wavelength in the final tabulation is 0.050 A. Such lists are ideally suited for line identification work using the method of wavelength coincidence statistics (WCS). The results of WCS studies of the ultraviolet spectra of the chemically peculiar (CP) stars iota Coronae Borealis and kappa Camcri. Aside from confirming a number of previously reported aspects of the abundance patterns in these stars, the searches produced some interesting, new discoveries, notably the presence of Hf in the spectrum of kappa Camcri. The implications of this work for theories designed to account for anomalous abundances in chemically peculiar stars are discussed.

Davidson, J. P.↗
NASA NTRS1982

The violet interstellar medium associated with the Carina Nebula

The interstellar spectrum of HD 93205, an 03V star in the cluster Tr16, located inside the most active part of the Great Carina Nebula was analyzed using data extracted directly from raw IUE images. From the analysis of 67 lines of 25 atoms, ions and molecules, up to six discrete absorption components spanning a maximum velocity range of approximately 375 km 5/1 were identified. The component structure for different species is tabulated and sample absorption lines, indicating at the top the positions of the six components, labelled A to F are shown. Ion column densities appropriate to each component which can be resolved in at least one line were derived by constructing empirical curves of growth and by fitting the observations with corresponding theoretical absorption line profiles. The most important results concerning each component are discussed.

Pettini, M.↗
NASA NTRS1981

Radio observations of Abell clusters and a comparison with certain Einstein observations

Areas around 70 clusters have been observed at the Arecibo Observatory primarily for coordination with about 60 Einstein X-ray sources. Arecibo source coordinates and flux density are tabulated, and some identifications are made with cataloged radio sources. Statistical estimates are made of the percentage of cluster sources among all sources in certain areas and to limits on the flux density of 430 MHz. Arecibo and other radio data are compared with the available Einstein data of seven clusters. Not every Einstein source has a radio counterpart, and the counterparts may variously be bilobed, tailed, or single. A parameter which is proportional to source continuum power at 430 MHz ranges over fewer orders of magnitude than the associated source X-ray luminosity, with no certain correlation between these parameters. NRAO Green Bank interferometer observations of A401 and A2142 are reported.

Johnson, H. M.↗
NASA NTRS1981

Molecules in interstellar clouds

The physical conditions and chemical compositions of the gas in interstellar clouds are reviewed in light of the importance of interstellar clouds for star formation and the origin of life. The Orion A region is discussed as an example of a giant molecular cloud where massive stars are being formed, and it is pointed out that conditions in the core of the cloud, with a kinetic temperature of about 75 K and a density of 100,000-1,000,000 molecules/cu cm, may support gas phase ion-molecule chemistry. The Taurus Molecular Clouds are then considered as examples of cold, dark, relatively dense interstellar clouds which may be the birthplaces of solar-type stars and which have been found to contain the heaviest interstellar molecules yet discovered. The molecular species identified in each of these regions are tabulated, including such building blocks of biological monomers as H2O, NH3, H2CO, CO, H2S, CH3CN and H2, and more complex species such as HCOOCH3 and CH3CH2CN.

Irvine, W. M.↗
NASA NTRS1982

Diffusion and viscosity coefficients for helium

The first order Boltzmann-Fokker-Planck equation is solved numerically to obtain diffusion and viscosity coefficients for a ternary gas mixture composed of electron, protons, and helium. The coefficients are tabulated for five He/H abundances ranging from 0.01 to 10 and for both He II and He III. Comparison with Burgers's thermal diffusion coefficients reveals a maximum difference of 9-10% for both He II and He III throughout the range of helium abundances considered. The viscosity coefficients are compared to those of Chapman and Cowling and show a maximum difference of only 5-6% for He II but 15-16% for He III. For the astrophysically important gas mixtures, it is concluded that the results of existing studies which employed Burgers's or Chapman and Cowling's coefficients will remain substantially unaltered.

Roussel-Dupre, R.↗
NASA NTRS1982

Long cloud observations on Mars and implications for boundary layer characteristics over slopes

The times and locations of occurrence are measured, as are the wavelengths and, when possible, the apparent velocity of motion of these clouds. The wavelengths of the patches of ripple clouds that are often found with the long formations are tabulated. The long clouds are observed only in the early morning hours, suggesting that they are associated with drainage winds caused by a cold planetary boundary layer. Simple mathematical models are developed to examine various aspects of such boundary winds; these make it possible to construct a complete and self-consistent explanation of all the observed features of the cloud formations.

Kahn, R.↗
NASA NTRS1982

Application of the line-spring model to a cylindrical shell containing a circumferential or axial part-through crack

The line-spring model developed by Rice and Levy (1972) is used to obtain an approximate solution for a cylindrical shell containing a part-through surface crack. A Reissner type theory is used to account for the effects of the transverse shear deformations, and the stress intensity factor at the deepest penetration point of the crack is tabulated for bending and membrane loading by varying three-dimensionless length parameters of the problem formed from the shell radius, the shell thickness, the crack length, and the crack depth. The upper bounds of the stress intensity factors are provided, and qualitatively the line-spring model gives the expected results in comparison with elasticity solutions.

Delale, F.↗
NASA NTRS1982

Thermal stability of the surface layer and its relation to the dispersion of primary pollutants in St. Louis

The present investigation is concerned with the applicability of the vertical temperature gradient, DT, as a dispersion parameter for urban area sources. Data on DT were tabulated from temperature measurements at 5 m and 30 m obtained on 30 m towers at 12 stations. DT was obtained by subtracting the value at 5 m from that at 30 m. Positive DT values represent an inversion. Accuracy of the DT data is 0.1 K. Hourly measurements of DT along with concentrations of the primary pollutants, CO, NO, and total hydrocarbons (THC), are available from the 1976 RAPS data base for St. Louis. Linear correlations between a given pollutant species concentration and DT are developed from that data set. It could be confirmed that a strong positive correlation exists at night between the thermal stability of the lowest part of the boundary layer and the urban concentration of the primary pollutants CO, NO, and hydrocarbons.

Remsberg, E. E.↗
NASA NTRS1982

The ionization equilibrium of astrophysically abundant elements

The paper presents new calculations of ionization equilibrium fractions of 11 abundant elements (C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni) as functions of temperature. Convenient coefficients for fitting the rates of collisional ionization, radiative recombination, and dielectronic recombination are also tabulated. Many of the ionization rates are based on recent experimental measurements of cross sections for collisional ionization and autoionization following inner-shell excitation. These rates are used elsewhere in computations of nonequilibrium ionization, radiative cooling, radiative shock models, and plasma emission diagnostics.

Shull, J. M.↗
NASA NTRS1982

An accurate and efficient method for evaluating the kernel of the integral equation relating pressure to normalwash in unsteady potential flow

This paper describes an accurate economical method for generating approximations to the kernel of the integral equation relating unsteady pressure to normalwash in nonplanar flow. The method is capable of generating approximations of arbitrary accuracy. It is based on approximating the algebraic part of the non elementary integrals in the kernel by exponential approximations and then integrating termwise. The exponent spacing in the approximation is a geometric sequence. The coefficients and exponent multiplier of the exponential approximation are computed by least squares so the method is completely automated. Exponential approximates generated in this manner are two orders of magnitude more accurate than the exponential approximation that is currently most often used for this purpose. Coefficients for 8, 12, 24, and 72 term approximations are tabulated in the report. Also, since the method is automated, it can be used to generate approximations to attain any desired trade-off between accuracy and computing cost.

Desmarais, R. N.↗
NASA NTRS1982

Identification of Fe I lines in the ultraviolet solar spectrum

High-resolution ultraviolet echelle spectrograms of the sun obtained from a rocket-borne spectrograph have been used for the identification of Fe I absorption lines in the wavelength range 1770-2020 A. Wavelength measurements, with a precision of about 15 mA, are tabulated for 425 Fe I features, along with available laboratory wavelenghs or predicted wavelengths calculated from atomic energy level data. The classification system of Moore has been extended to include possible additional multiplets with 126 newly classified lines; 234 unclassified lines were observed and identified with laboratory Fe I spectra

Mccabe, M. K.↗
NASA NTRS1982

IUE low-dispersion spectra of six luminous stars in symmetric nebulae

The stars and nebulae are HD 156738 and HDE 319703A, respectively centered in a pair of symmetric nebulae among the NGC 6334 group, AG Car in its nebula, HDE 250550 in nebula 8 of a catalog by Herbig, 209 BAC in Ml-67, and HD 89358 in NGC 3199. These include two O stars, two WN stars, an unstable B supergiant, and a ZAMS B star. Four of them are additions to a previous similar study, and the information about AG CAR and 209 BAC/Ml-67 is extended from that study. The objects are interpreted with Weaver et al.'s (1977) theory of the interaction of a stellar wind with the ambient interstellar medium, except where the short lifetime of the HDE 250550 nebula has forestalled such analysis. Spectral line identifications and types, and several parameters of mass loss, are tabulated. When the present mass loss rates are compared with previous results from other methods, there is an outstanding difference only for WN stars, since 1-3 x 10 to the -7th solar masses/year is derived here.

Johnson, H. M.↗
NASA NTRS1982

Resonances in Saturn's rings

The locations and strengths of the major resonances of Saturn's known moons with particles orbiting within Saturn's rings are calculated. The resonant effects of an outer satellite on Saturn's rings is analyzed by Fourier expanding the satellite's potential, and it is found that the forcing at an l:(m-1) resonance depends on the moon's eccentricity to the (l-m) power. As most of Saturn's inner moons are in very nearly circular orbits, only their strongest resonances, with l = m and l = m+1, are calculated. For Mimas, which has a somewhat larger eccentricity, resonances with l = m+2 are also computed. All of the resonances of these forms which are located between Saturn's cloud tops and 2.267 Saturn radii are tabulated, except some of those due to tiny 1980 S28.

Lissauer, J. J.↗